Polish President and wife killed in Tu-154 crash

[Gabriel]

I guess I read it as "2 to 3 times the descent rate" instead of "2 to 3 times descent angle".

In the last part of their approach the descent rate was 7.18 m/s. Between points 10:40:40.0 and 10:40:56.0. This is the highest descent rate of the whole approach and it is 51% higher than upper range normal.

Between the outer NDB and 100m alt the descent rate was 44% above the upper range normal. This is still high. I just did not want anyone to read it as 2 to 3 times the normal descent rate.

But even if you look at the descent angle, it is 4deg36' between outer NDB and the 100m alt point, and 5deg17' for the rest. So at the steepest section it is 1.98 times normal and 1.66 times upper range normal. I know I am splitting hair, but 2 to 3 times seems much worse.

Without question though, the approach was not stabilized.

Well, something doesn't add up here:

- 2 times the slope at the same speed MUST lead to 2 times the descent rate.
- If the speed is faster than the normal one, then the descent rate at the right slope is faster than, and at the wrong slope it is even more wrong than the slope alone can explain.
- This plane was flying a steeper approach than normal and faster than normal. There is no way for a 2 times the slope and 1.5 times the descent rate to co-exist.
- Forget about the 100m point. There is a clear straight slope (well, pretty straight), steeper than normal, from the beginning of the descent to about 200m QFE, a clear break at that point (a vertex if you will), and then another even steeper clear pretty straight slope from that point until the beginning of the pull-up.
- Look at the trinagles again. It clearly shows a more than twice the normal slope, wich combined with the faster speed leads to an even higher descent rate. Unless the "accurate fligth path" (in your words) is not that, the descent rate from 200m on was more than twice normal, and hence between 2 and 3 times.

So, if what you say is right, then the "accurate" plot is wrong. If the accurate plot is, well, accurate, then what you say is wrong.

[Northwester]

Well, something doesn't add up here:

- 2 times the slope at the same speed MUST lead to 2 times the descent rate.
- If the speed is faster than the normal one, then the descent rate at the right slope is faster than, and at the wrong slope it is even more wrong than the slope alone can explain.
- This plane was flying a steeper approach than normal and faster than normal. There is no way for a 2 times the slope and 1.5 times the descent rate to co-exist.
- Forget about the 100m point. There is a clear straight slope (well, pretty straight), steeper than normal, from the beginning of the descent to about 200m QFE, a clear break at that point (a vertex if you will), and then another even steeper clear pretty straight slope from that point until the beginning of the pull-up.
- Look at the trinagles again. It clearly shows a more than twice the normal slope, wich combined with the faster speed leads to an even higher descent rate. Unless the "accurate fligth path" (in your words) is not that, the descent rate from 200m on was more than twice normal, and hence between 2 and 3 times.

So, if what you say is right, then the "accurate" plot is wrong. If the accurate plot is, well, accurate, then what you say is wrong.

This is becoming a real slope war now

If I use your points, this is what I get:

Between outer NDB and 200m alt - 6.195m/s vs. 4.0915m/s (51% higher)
(the slope - 4deg2' vs. 2deg40' (51% higher)

Between 200m alt and last measurable point (see attached)
7.79m/s vs. 3.66m.s (2.12 times)
5deg39' vs. 2deg40' (2.12 times)

So you win. Happy now?

[Gabriel]

This is becoming a real slope war now

If I use your points, this is what I get:

Between outer NDB and 200m alt - 6.195m/s vs. 4.0915m/s (51% higher)
(the slope - 4deg2' vs. 2deg40' (51% higher)

Between 200m alt and last measurable point (see attached)
7.79m/s vs. 3.66m.s (2.12 times)
5deg39' vs. 2deg40' (2.12 times)

So you win. Happy now?

Quite. But not fully yet.

1) For the second segment, don't take "the last measurable point". The pull-up had already began there. Look where I placed the point of the triangles. You'll find that the slope is a little steeper (and also the descent rate of course).

2) For the descent rate, apply a V(real)/Vref factor. You calculated the "normal" descent rate as the rate at the "target slope", but you have to accunt for the "target speed" too. Flying the normal slope at a speed faster than normal leads to a higher than normal descent rate.

After applying 1 and 2 you'll find that the factor is 2.4 / 2.5, which is very well described as somewhere between 2 to 3 times.

3) For the first segment, it's not smething that I care about, but don't take the outer marker, take the point where the descent is already established. And the Vref factor also plays here.

Both in the first and second segment you'll see that the plots don't fit very well your staright line. Not as well as if you start after / end before those transition points.

[Northwester]

Quite. But not fully yet.

1) For the second segment, don't take "the last measurable point". The pull-up had already began there. Look where I placed the point of the triangles. You'll find that the slope is a little steeper (and also the descent rate of course).

2) For the descent rate, apply a V(real)/Vref factor. You calculated the "normal" descent rate as the rate at the "target slope", but you have to accunt for the "target speed" too. Flying the normal slope at a speed faster than normal leads to a higher than normal descent rate.

After applying 1 and 2 you'll find that the factor is 2.4 / 2.5, which is very well described as somewhere between 2 to 3 times.

3) For the first segment, it's not smething that I care about, but don't take the outer marker, take the point where the descent is already established. And the Vref factor also plays here.

Both in the first and second segment you'll see that the plots don't fit very well your staright line. Not as well as if you start after / end before those transition points.

Well, this is turning into a number game, I suppose. I could easily, using normal parameters, show that it is less.

Normal approach speed for Tu-154 is 138-148 knots. So I could use 148 knots which is 274 km/h. Their speed for the section shown was 285.5 km/h. That's 4.2% higher than normal.

I could also assume that 3deg10' is within the normal range of approach slope. So the normal descent rate would be 105.3101 (alt diff) / 24sec = 4.39 m/s. Adjusted for Vref - 4.21 m/s.

Their descent rate was 197.0102 / 24 sec = 8.20 m/s. That is 1.95 times normal.

It is more important to find out why, after they intercepted the correct approach path at 200m alt, they continued to descend at high rate till they almost touched the ground below the RWY elev.

[Gabriel]

Well, this is turning into a number game, I suppose. I could easily, using normal parameters, show that it is less.

Normal approach speed for Tu-154 is 138-148 knots. So I could use 148 knots which is 274 km/h. Their speed for the section shown was 285.5 km/h. That's 4.2% higher than normal.

I could also assume that 3deg10' is within the normal range of approach slope. So the normal descent rate would be 105.3101 (alt diff) / 24sec = 4.39 m/s. Adjusted for Vref - 4.21 m/s.

Their descent rate was 197.0102 / 24 sec = 8.20 m/s. That is 1.95 times normal.

I have no objection to the above. I was simply explaining the rationale behind my "2 to 3 times" that had been objected by you.

[Gabriel]

It is more important to find out why, after they intercepted the correct approach path at 200m alt, they continued to descend at high rate till they almost touched the ground below the RWY elev.

I agree. But let me restate the above:

It is more important to find out why, after they intercepted the upper bound of the correct approach path at 200m alt, they continued to descend at an even-higher-than-before rate (instead of reducing it to follow the correct path) till they almost touched the ground below the RWY elev.

The upper bound of the tolerance of the glide path would be equivalent, I guess, as flying at nearly full scale deflection in the glide slope in an ILS.

One thing to consider. They probably never knew that they were intercepting the upper bound, then the nominal slope, and then the lower bound. As I've said, they probably were not flying with vertical guidance, so a "glide slope" is more a theoretical construction or something that we can reconstruct afterwards than a tool they had for the navigation.

[Northwester]

I wonder if there is a way to find out from the FMS unit settings (or FDR) if they were using any kind of vertical guidance or not. I don't remember any comments referring to it.

[Evan]

I wonder if there is a way to find out from the FMS unit settings (or FDR) if they were using any kind of vertical guidance or not. I don't remember any comments referring to it.

There is a way. You could read the report.

The FMS vertical navigation mode was not engaged and there was no flight plan for vertical navigation.

[Northwester]

There is a way. You could read the report.

Since you are one of the most experienced people here, what would be your possible explanation of what happened after the 200m call (straight steep descent to 0m)?

[Curtis Malone]

Since you are one of the most experienced people here, what would be your possible explanation of what happened after the 200m call (straight steep descent to 0m)?

You asked a question, and Evan pointed out to you where the report contained the answer. No need to get snippy, unless you don't believe anything in said report, which I suspect is the case.

[Northwester]

You asked a question, and Evan pointed out to you where the report contained the answer. No need to get snippy, unless you don't believe anything in said report, which I suspect is the case.

Overinterpretation (is there such word?). I was not snippy, just curious. I am assuming that all parts of the report are true unless proven otherwise. The CVR transcript is one where the differences are significant.

But about the approach, there is one theory that says that the approach speed was higher than normal because the pilots never intended to land. Some other speculate about what role the false readings of the electronic altimeter might have played. And of course the calls from the ATC about being 1km closer to the RNWY and on course and path.
Some say that the coordinates of the RNWY must have been wrong.

What information did they have about the distance to the RNWY? At some point before the outer NDB the captain says "4". What does that mean? Most likely it indicates the distance to the RNWY. Is he still using miles?

[Evan]

Since you are one of the most experienced people here, what would be your possible explanation of what happened after the 200m call (straight steep descent to 0m)?

Honestly, I'm not even following this 'glideslope' argument because...

a) there was no glideslope, only a prescribed glidepath angle, which they were never on (but within radar tolerance of);

b) therefore you might as well be arguing about tire pressure;

c) You haven't studied pg 156 of the report.

The callouts were read from the radar altimeter. You need to start there.

[guamainiac]

Evan, there are still questions that remain unanswered and just a quick read of the Wiki ... please restrain the sniggering and cat calls for later when they are fully appropriate.

- The controllers radar was not calibrated and showed erroneous readings

- Trees were cut down after the crash because the Smolensk strip was not compliant with even Russian standards

- There was supposed to be some "Command Guy" but he was there only a few, like seven times. They were questioning his ability to "Command" especially under bad conditions. Was he the guy who was supposed to order the strip shut down or the ATC the authority to order the flight to divert.

- Was the pilot, and in my muddled brain, aware that the flight was to have been treated as a military flight, and/or where is the documentation that it would or should have been treated as civilian aviation.

I really can't get this through my mind. If all international protocols dictate that the ATC has the command authority to call off the approach why this talk of "Chicago" protocols since this is post mortem and post facto for God sake?

If flight after flight after flight you operate under the "MIL-SPEC" .. (attempt at humor), who changed the rules, if indeed they did. Now, this does indeed factor if you have ATC with a faulty scope that indicated that the flight is closer to the runway than it actually is ATC thinks things are fine at that particular elevation and distance but the problem here is that the distance is off.

When the ATC .. and yes I am aware that the TAWS is yakking away too, but with ATC calling the shots (military rules), the PIC has not only the pressure from the General but Wiki also indicated another voice as that of The Director of Protocol.

This is the moment every pilot dreams of to show that they are indeed made of "The Right Stuff" .... questionable authority as to the status (closed or open) of the field, a scope jockey with a bad scope, IFR up the wazoo, a Franco Wannabee, and Emily Post checking that the knives and forks on the flight deck were; or what the f' a "Director of Protocol" does on the flight deck.

No mention of the goofy searchlights however.

This is a classic "cascade-of-a-cluster-fukk".

Who was actually in control of the flight during those last moments?

The box telling you that there is conflict ... the ATC ... or the PIC.

How often (or do you?), use a GPS in your car? Admit it, one of the most difficult things to get across when you are with someone who does not know the area is telling or getting across the notion to ignore "the beeoch in the box". Why do you think they have all of those disclaimers just to turn the thing on? In behavioral psych would this be an approach-avoidance-double avoidance conflict or .... on this part I am quite serious, look at the complexity of the nature of the sequence of authority and the compressed time to make a decision and sort it out. This is where the "lines" converge and where technology, "the rules" (but which ones), and the social hierarchy meet. Oh! Now I understand the presence of "The Director of Protocol" and he or she was to have sorted this all out.

No, this ain't as we would have said in the military ... "one and done, time to go home" .... sounds like the Russian have left a lot of critical questions unanswered. The Polish did admit that the pilot was not without blame and said so in no uncertain terms but, in so critical a chain of decision making it sounds like they tossed in a few ringers that ... had they not patched this mess together this whole thread would be unnecessary.

[guamainiac]

What happens when .. In the old days of wooden ships and iron men ?? ..

In US carrier ops the LSO was advisory. The Landing Safety Officer aka "Paddles" would make gestures with paddles .. high or low, wing down and such.

In UK carrier ops the LSO was mandatory and the final authority.

Enter the Optical Landing System or "the balls" .. and this is good because now the human factor has been taken out. I have done approaches with some primitive systems using a series of boards and they are pretty cool in maintaining the glide path.

But, when the OLS kicks in the accident rate goes way up. The best way to do it was the combination of OLS (lights), and LSO.

My point ... you are on approach (remember the US versus UK rules), and you are waiting for confirmation .... now in our case, the nice lady in the box is telling you to "pull up, pull up" ... but old "Paddles" is just standing there not doing (in our case ATC), saying much of anything. The protocol is for human and mechanical annunciation ... you pause and ...

Wait for more information?

And cabin boy? Where is that little blighter when I want him?

[Evan]

Evan, there are still questions that remain unanswered and just a quick read of the Wiki ... please restrain the sniggering and cat calls for later when they are fully appropriate.

Why are we going on with this? I still don't see the any angle that would lesson the essence of the findings, which contain numerous and inexcusable shortcomings, violations and errors on the part of the Polish government and the pilots themselves. But put these things aside for a minute and just consider this...

- Did the Polish think they were flying into a active commercial airport with modern navaids and standard maintenance? No, they were fully aware of the derelict state of the aerodrome. They had flown there three days earlier. Item nullified.

- Was this a radar guided approach? No, that would be insane, given the known condition of the aerodrome and its equipment. This was an approach using autonomous on-board guidance alone. Item nullified.

- Were they required to continue the approach because of some military requirement that they must let ATC make the call? No, they were not part of the Russian military, and were in fact, as the air transport of the head of a sovereign state, immune from any such requirement. They had complete diplomatic autonomy to reject the approach at any time. Item nullified.

- Was the landing radar discrepancy enough to prevent the pilots from flying the approach using on-board instruments, or from rejecting the approach when the runway failed to appear at MDA. No. Item nullified.

The best you could say here (using the preposterous argument that they were on a radar guided approach, and indifferent to their own nav instruments) is that the Russian ATC, using a vintage, non-precise radar system, placed them in the wrong location at MDA. That doesn't crash an airplane. That just results in a missed approach.

Unless egregious pilot error is involved.